1. FIELD OF THE INVENTION
This invention relates to a relatively low cost, disposable and sterilizable syringe which is adapted to reduce the frequency of accidental and, in some cases, life threatening needle strikes by enabling selective position control of the needle cannula from a position projecting outwardly and distally from the syringe cylinder at which to administer an injection to a retracted and locked position within the cylinder at which the syringe may be safely handled and discarded after use.
2. PRIOR ART
Hypodermic syringes are used for a variety of injection procedures including the delivery of medicinal drugs and anesthetics to a recipient. However, once the injection procedure is completed and the syringe cylinder emptied, problems may arise as a consequence of failing to properly and adequately dispose of the syringe. By way of an example, the syringe may be used to treat a patient having a communicable disease. To prevent reuse, the hypodermic needle is sometimes broken before the syringe is discarded. Health care workers are susceptible to accidental and potentially infectious needle strikes due to the careless handling of the hypodermic needle from breaking the needle or disposing of the syringe after use. The resulting mini-accidents caused by the inadvertent needle strikes typically require a blood test for such diseases as AIDS and hepatitis. The corresponding cost and inefficiency of testing health care workers who have received an inadvertent needle strike results in considerable waste, which may be particularly damaging to a health care facility striving for economy and efficiency.
The following U.S. patents provide examples of syringes having a hypodermic needle which may be withdrawn into the syringe cylinder after use:
U.S. Pat. No. 2,722,215, Nov. 1, 1955 PA1 U.S. Pat. No. 4,026,287, May 31, 1977 PA1 U.S. Pat. No. 4,507,117, Mar. 26, 1985 PA1 U.S. Pat. No. 4,643,199, Feb. 17, 1987 PA1 U.S. Pat. No. 4,650,468, Mar. 17, 1987
One significant problem with some of the syringes listed above lies in the fact that said syringes have no means by which a used hypodermic needle may be safely locked within and permanently shielded by the syringe cylinder, so that the syringe and needle are not easily reuseable. That is to say, little is available in the aforementioned syringes to prevent the needle from being completely removed from the syringe cylinder and/or from being returned to an outwardly projecting position from the cylinder by which to execute another injection procedure. Consequently, the syringe and/or needle may be reused. A greater opportunity exists to handle a used needle which has been removed from or returned to the cylinder, so as to disadvantageously contribute to an accidental needle strike and to the possible spread of disease.